Polysulfide treated molecular sieves and use thereof to remove mercury from liquefied hydrocarbons

Abstract

Disclosed herein is a process for removing contaminating mercury from hydrocarbon streams, gas or liquid, wherein the stream is contacted with a molecular sieve pretreated with an alkali polysulfide. The pretreatment consists of saturating the sieve with an aqueous solution of the polysulfide and subsequently drying the saturated sieve under conditions calculated to dry but not decompose the polysulfide present.

What is claimed is: 
     
       1. A process for preparing a molecular sieve absorbent comprising: (a) drying a molecular sieve at a temperature of between about 350° and about 450° C. in an anhydrous nonreactive atmosphere;   (b) contacting said molecular sieve with an aqueous solution of water soluble alkali polysulfide until said molecular sieve is saturated with said aqueous solution; and   (c) drying said saturated molecular sieve of (b) at a temperature between about 10° and about 75° C. and a pressure of less than about 500 millimeters of mercury to deposit said water soluble alkali polysulfide onto said molecular sieve without decomposing the water soluble alkali polysulfide.   
     
     
       2. The process of claim 1 wherein the molecular sieve is selected from the group consisting of sodium zeolite X, sodium zeolite Y, zeolite beta and zeolite 20. 
     
     
       3. The process of claim 1 wherein the molecular sieve is a synthetic faujasite. 
     
     
       4. The process of claim 1 wherein the molecular sieve is sodium zeolite X. 
     
     
       5. The process of claim 1 wherein said alkali sulfide is sodium polysulfide containing between about 5 and about 25% sulfur. 
     
     
       6. The process of claim 1 wherein said saturated product of (b) is dried in a two step process wherein the first step comprises drying the molecular sieve at a temperature between about 10° and about 30° C. and a reduced pressure and subsequently drying the resulting product at a temperature between about 30° and about 75° C. under a pressure of about 1 millimeter of mercury. 
     
     
       7. The process of claim 1 wherein the concentration of sulfur in the alkali polysulfide is between about 5 and about 25% by weight. 
     
     
       8. An absorbent suitable for removing mercury from a gaseous liquid hydrocarbon stream or gaseous stream comprising the product produced by: (a) drying a molecular sieve at a temperature of between about 350° and about 450° C. in anhydrous nonreactive atomsphere;   (b) contacting said molecular sieve with an aqueous solution of water soluble alkali polysulfide until said molecular sieve is saturated with said aqueous solution; and   (c) drying said saturated molecular sieve of (b) at a temperature of between about 10° and about 75° C. and a pressure of less than about 500 millimeters of mercury to deposit said water soluble alkali polysulfide onto said molecular sieve without decomposing the water soluble alkali polysulfide, wherein said molecular sieve is selected from the group consisting of sodium zeolite x, sodium zeolite y, zeolite beta, zeolite 20, and synthetic faujasite.   
     
     
       9. The product of claim 8 wherein said alkali sulfide is sodium polysulfide containing between about 5 and about 25% sulfur. 
     
     
       10. The product of claim 8 wherein said saturated product of (b) is dried in a two step process wherein the first step comprises drying the adsorbent at a temperature between about 10° and about 30° C. and a reduced pressure and subsequently drying the resulting product at a temperature between about 30° and about 75° C. under a reduced pressure of 1 millimeter. 
     
     
       11. The product of claim 8 wherein the concentration of sulfur in the alkali polysulfide is between about 5 and about 25% by weight.